This invention relates to fuser and pressure roller type fusing stations for fusing toner images in electrostatographic copiers and printers. More particularly, the invention relates to a method and apparatus for applying fusing oil to a toner image contacting surface of such a fusing station.
Fuser and pressure roller type fusing stations are well known for fusing toner images on a suitable receiver in electrostatographic copiers and printers. Usually the fuser roller of such stations is heated, and rotatably forms a fusing nip with a pressure roller. Receiver sheets carrying unfused toner images thereon can then be passed one at a time through such a fusing nip such that the surface of the heated fuser roller directly contacts and heats the toner images on each receiver sheet.
A common problem associated with such fusing stations is the undesirable offsetting of toner particles forming the toner images from the receiver sheet onto the surface of the fuser roller. Such offsetting of the toner particles results in poor image quality. In order to prevent such offsetting, it is well known to apply a toner release or fusing oil such as silicone oil, to the surface of the fuser roller.
Some of the various methods and apparatus for applying such oil to the surface of the fuser roller are disclosed, for example in U.S. Pat. No. 3,982,832 issued to Bendall et al. on Sep. 28, 1976, U.S. Pat. No. 4,393,804, issued to Nygard et al on Jul. 19, 1983, Great Britain Patent Specification No. 1,399,740, Published Jul. 2, 1975 and U.S. Pat. No. 4,994,862, issued Feb. 19, 1991 to Hoover. Typically, the apparatus disclosed each include a member for contacting and applying fusing oil to the fuser roller surface, and a supply source such as a replenishment bottle, for supplying fusing oil to the oil applying member. As such, the oil applying member becomes contaminated through- such contact and must occasionally be replaced. The supply source of oil frequently also has to be renewed. Furthermore, each such apparatus includes a separate and dedicated drive means, such as a motor, for powering the means for feeding the oil from the supply source to the oil applying member. Such apparatus are expensive, and are often difficult for ordinary operators to handle. In addition, the oil applying member by becoming contaminated can result in non-uniform oil application if not timely replaced.